GMC SMTP Mailer — Documentation (WordPress)
GMC SMTP Mailer is a free WordPress plugin that routes every email your site sends — form notifications, password resets, order and booking mail — through your own authenticated SMTP account instead of the web server's anonymous PHP mail. Because delivery happens at the phpmailer_init level, it applies to all plugins with no theme or code changes, and messages carry your mail domain's SPF/DKIM authentication. Configuration is intentionally lean: there is no extra admin screen — settings are managed through administrator-only REST endpoints, which makes the plugin scriptable and a natural fit for developers and professionally maintained sites. Requirements: WordPress 6.0 or newer, PHP 7.4 or newer.
Installation
- In your dashboard go to Plugins → Add New Plugin → Upload Plugin.
- Choose the plugin
.zipfile (keep it zipped — do not extract it). - Click Install Now, then Activate.
After activation the plugin does nothing until you configure it and set enabled to true, so activating it on a live site is safe.
Configuration
All settings are read and updated through the REST endpoint gmc-smtp-mailer/v1/settings. Only users with the manage_options capability (administrators) can read or change them. The simplest way to authenticate is a WordPress Application Password for an administrator account, used with any REST client. Example request:
curl -X POST https://example.com/wp-json/gmc-smtp-mailer/v1/settings -u "admin:APPLICATION PASSWORD" -H "Content-Type: application/json" -d '{"host":"mail.example.com","port":587,"secure":"tls","username":"noreply@example.com","password":"your-smtp-password","from_email":"noreply@example.com","from_name":"Example Site","enabled":true}'
A GET request to the same endpoint, with the same authentication, returns the current configuration. The available fields:
host— your SMTP server hostname.port— the SMTP port your provider uses.secure— the encryption mode, TLS or SSL.username/password— the credentials of the SMTP account (your hosting mailbox or any provider).from_email/from_name— the From address and From name applied consistently to every message, whichever plugin sends it.enabled— switches SMTP routing on or off.
Testing delivery
Before relying on the plugin, confirm real delivery end to end with the test endpoint:
curl -X POST https://example.com/wp-json/gmc-smtp-mailer/v1/test -u "admin:APPLICATION PASSWORD"
This sends an actual test message through your configured SMTP account — not a simulation — so you can check that it arrives in the target inbox. Like the settings endpoint, it is restricted to administrators. If the test message does not arrive, re-check the values you sent to the settings endpoint (host, port, secure mode and credentials) and run the test again.
Updates & licence
GMC SMTP Mailer is free and GPL-licensed. Automatic updates are self-hosted: the plugin checks the GMC / FuerteventuraTV update server on its own and offers new versions under Plugins or Dashboard → Updates like any other plugin. No licence key is required at any point.
Uninstalling is clean: when you delete the plugin, the stored SMTP credentials and the cached update metadata are removed from the database.
Support
Support is handled on WhatsApp: +34 633 168 995. We answer in English, Italian and Spanish.
To get a useful answer quickly, include:
- the plugin version,
- your WordPress and PHP versions,
- what you sent to the settings endpoint — with the password masked.
Everything included
21 real capabilities, grouped by area — the full depth of what GMC SMTP Mailer does.
Authenticated SMTP delivery
- Real SMTP for every WordPress email — routes all site mail (form notifications, password resets, order and booking mail) through your own authenticated SMTP account at the
phpmailer_initlevel, instead of the web server's anonymous PHP mail. - No theme or plugin changes — delivery is switched at the mail layer, so every plugin that calls
wp_mail()is covered at once with nothing to edit. - Full transport control — set host, port, encryption (TLS, SSL or none), username and password, all from one settings object.
- Consistent sender identity — one From address and one From name applied across every plugin that sends mail (
wp_mail_from/wp_mail_from_name), so outgoing mail always looks like it comes from you. - Sensible defaults — the From address falls back to your admin email and the From name to your site name, so a minimal config still sends correctly.
- Safe when incomplete — SMTP only takes over when it is enabled and host, username and password are all present; otherwise WordPress keeps sending as before, so a half-finished setup never blocks your mail.
- Inbox-grade authentication — because mail leaves your own mailbox it carries your domain's SPF/DKIM, the real reason messages stop landing in spam.
Test send & verification
- One-call delivery test — a dedicated
/testREST endpoint sends a real message through your SMTP account so you can confirm end-to-end delivery before you rely on it. - Recipient and content validated — the test checks the recipient is a valid email address and cleans the subject and body before sending.
- Clear pass/fail result — the test reports whether the message was actually sent, alongside the current (password-free) settings.
Admin-only REST management
- Scriptable settings API — read and update the whole configuration through the
gmc-smtp-mailer/v1/settingsendpoint, a natural fit for developers and automated deploys. - Administrator lock — every endpoint requires the
manage_optionscapability, so only site administrators can read or change mail settings. - Password never exposed — the API returns settings with the password stripped out and only a
password_setflag, so credentials can't leak back through a read. - Hardened inputs — hostnames are reduced to safe characters, the port is bounds-checked (1-65535), the encryption mode is whitelisted, and the From address must be a valid email or the update is rejected.
- Lightweight storage — settings are saved without autoload, so they add no weight to every page request.
Updates, cleanup & trust
- Self-hosted automatic updates — bridges the WordPress plugin-update API to the GMC / FuerteventuraTV gateway, so new versions appear under Plugins / Dashboard → Updates like any other plugin — no licence key required.
- Vendor-locked, HTTPS-only downloads — update packages are accepted only over HTTPS on port 443 from the
fuerteventuratv.netdomain, and only when the offered version is strictly newer. - Efficient checks — update metadata is cached for 12 hours with a short timeout and a capped response size, keeping the check cheap and non-blocking.
- Clean uninstall — deleting the plugin removes the stored SMTP credentials and cached update data from your database.
- Free and GPL — released under GPL-2.0-or-later at no cost; runs on WordPress 6.0+ and PHP 7.4+.
- Trilingual support — help and support answered in English, Italian and Spanish.
